Clutch unit

ABSTRACT

A clutch unit includes a lever-side clutch portion for controlling transmission and interruption of rotational torque to an output side through lever operation, and a brake-side clutch portion for transmitting torque input from the lever-side clutch portion to the output side and for interrupting torque reversely input from the output side. The lever-side clutch portion has an outer centering spring provided between a lever-side outer ring to be rotated through the lever operation and a cover restricted in rotation, for accumulating an elastic force obtained by torque input from the lever-side outer ring and for restoring the lever-side outer ring to a neutral state with the accumulated elastic force through releasing of the torque input from the lever-side outer ring.

TECHNICAL FIELD

The present invention relates to a clutch unit having a lever-sideclutch portion for transmitting rotational torque from an input side toan output side thereof and a brake-side clutch portion for transmittingrotational torque from the input side to the output side andinterrupting torque reversely input from the output side.

BACKGROUND ART

In general, in a clutch unit using engagement elements such ascylindrical rollers or balls, a clutch portion is arranged between aninput-side member and an output-side member. Further, in the clutchportion, the engagement elements such as cylindrical rollers or ballsare engaged and disengaged with respect to wedge gaps formed between theinput-side member and the output-side member, thereby controllingtransmission and interruption of the input torque.

The applicant of the present invention has previously proposed a clutchunit incorporated into, for example, an automobile seat-lifter sectionwhich vertically adjusts a seat through lever operation. This clutchunit is provided with a lever-side clutch portion for transmittingrotational torque from the input side to the output side and abrake-side clutch portion for transmitting rotational torque from theinput side to the output side and interrupting torque reversely inputfrom the output side (see, for example, Patent Literature 1).

FIG. 40 is a longitudinal sectional view of an overall structure of theconventional clutch unit disclosed in Patent Literature 1, FIG. 41 is asectional view taken along the line D-D of FIG. 40, and FIG. 42 is asectional view taken along the line E-E of FIG. 40.

As illustrated in FIGS. 40 and 41, a lever-side clutch portion 111mainly includes a lever-side outer ring 114 serving as an input-sidemember to which torque is input through lever operation, an inner ring115 serving as a coupling member for transmitting the torque from thelever-side outer ring 114 to a brake-side clutch portion 112, aplurality of cylindrical rollers 116 serving as engagement elements forcontrolling transmission and interruption of the torque input from thelever-side outer ring 114 through engagement and disengagement betweenthe lever-side outer ring 114 and the inner ring 115, a retainer 117 forretaining the cylindrical rollers 116 at predetermined circumferentialintervals, an inner centering spring 118 serving as a first elasticmember which is provided between a brake-side outer ring 123 serving asa stationary-side member restricted in rotation and the retainer 117,for accumulating an elastic force obtained by the torque input from thelever-side outer ring 114 and restoring the retainer 117 to a neutralstate with the accumulated elastic force through releasing of the inputtorque, and an outer centering spring 119 serving as a second elasticmember which is provided between the lever-side outer ring 114 and thebrake-side outer ring 123, for accumulating an elastic force obtained bythe torque input from the lever-side outer ring 114 and restoring thelever-side outer ring 114 to the neutral state with the accumulatedelastic force through releasing of the input torque.

Note that, in the figures, reference numeral 113 represents a lever-sideside plate fixed to the lever-side outer ring 114 by swaging andconstituting the input-side member together with the lever-side outerring 114, and reference numeral 131 represents a washer mounted to anoutput shaft 122 through the intermediation of a wave washer 130.

Meanwhile, as illustrated in FIGS. 40 and 42, the brake-side clutchportion 112 mainly includes the brake-side outer ring 123 serving as astationary-side member restricted in rotation, the inner ring 115serving as a coupling member to which torque from the lever-side clutchportion 111 is input, and a plurality of pairs of cylindrical rollers127 serving as engagement elements arranged in wedge gaps 126 betweenthe brake-side outer ring 123 and the output shaft 122, for controllingtransmission of torque input from the inner ring 115 and interruption oftorque reversely input from the output shaft 122 through engagement anddisengagement between the brake-side outer ring 123 and the output shaft122.

Note that, there is provided a larger diameter portion 115 c extendingfrom an axial end portion of the inner ring 115 in a radially outerdirection and bending in an axial direction. In order to cause thelarger diameter portion 115 c to function as a retainer for retainingthe cylindrical rollers 127 at predetermined circumferential intervals,pockets 115 e for accomodating the cylindrical rollers 127 and platesprings 128 are equiangularly formed. In the figures, reference numerals124 and 125 respectively represent a cover and a brake-side side plateconstituting the stationary-side member together with the brake-sideouter ring 123, and the brake-side outer ring 123 and the cover 124 areintegrally fixed to each other with the brake-side side plate 125 byswaging. Reference numeral 128 represents a plate spring of, forexample, an N-shaped sectional configuration arranged between thecylindrical rollers 127 of each pair, and reference numeral 129represents a friction ring serving as a braking member mounted to thebrake-side side plate 125.

CITATION LIST

[PTL1] JP 2009-210114 A

SUMMARY OF INVENTION Technical Problems

By the way, the conventional clutch unit disclosed in Patent Literature1 has the following structure. Specifically, the stationary-side memberincludes the brake-side outer ring 123, the cover 124, and thebrake-side side plate 125, and the brake-side outer ring 123 and thecover 124 are integrally fixed to each other with the brake-side sideplate 125 by swaging. The conventional clutch unit also has thefollowing structure. Specifically, when the lever-side outer ring 114 isrotated through lever operation, the outer centering spring 119accumulates an elastic force obtained by torque input from thelever-side outer ring 114, and restores the lever-side outer ring 114 toa neutral state with the accummulated elastic force through releasing ofthe input torque. The outer centering spring 119 is provided between thelever-side outer ring 114 and the cover 124 constituting thestationary-side member together with the brake-side outer ring 123. Theouter centering spring 119 is held in abutment on the cover 124.

In a case of the clutch unit having the above-mentioned structure, whenthe lever-side outer ring 114 is rotated through lever operation, theouter centering spring 119 accumulates an elastic force obtained by thetorque input from the lever-side outer ring 114 and then increases indiameter. Then, at the time of lever operation of restoring a lever froma full stroke to a neutral position, the outer centering spring 119,which slides on the cover 124, may climb onto an inclined portion 124 gof the cover 124 (see FIG. 40) and thus come into contact with theopposing lever-side outer ring 114. When the outer centering spring 119climbs in this manner by sliding, the outer centering spring 119 comesinto contact with the lever-side outer ring 114, with the result thatslight noises may occur.

Further, as illustrated in FIG. 43, the above-mentioned outer centeringspring 119 is a C-shaped and band-like plate spring which includes apair of lock portions 119 a formed by bending both ends thereof to aradially outer side. One of the lock portions 119 a and the other of thelock portions 119 a are formed in such a manner that one slit is formedin a center region of each end of the outer centering spring 119 in aperipheral direction and one of both side parts of the slit is bent tothe radially outer side. Here, one of the lock portions 119 a is formedby bending the side part on one side in a band-plate width direction,and the other of the lock portions 119 a is formed by bending the sidepart on the other side in the band-plate width direction. Accordingly,at the time of application of input torque, such a moment force as topivot the other of the lock portions 119 a about a fulcrum set on theone of the lock portions 119 a is more likely to be generated. As aresult, a behavior of the outer centering spring 119 is not stabilized,which may cause occurrence of slight noises.

Therefore, it is an object of the present invention to provide a clutchunit capable of forestalling occurrence of noises caused at the time oflever operation by contact of the outer centering spring with thelever-side outer ring and by an unstable behavior of the outer centeringspring.

Solution to Problems

A clutch unit according to the present invention comprises: a lever-sideclutch portion provided on an input side, for controlling transmissionand interruption of rotational torque to an output side through leveroperation; and a brake-side clutch portion provided on the output side,for transmitting torque input from the lever-side clutch portion to theoutput side and for interrupting torque reversely input from the outputside.

The lever-side clutch portion according to the present inventioncomprises: an input-side member to be rotated through the leveroperation; and an elastic member provided between a stationary-sidemember restricted in rotation and the input-side member, foraccumulating an elastic force obtained by torque input from theinput-side member and for restoring the input-side member to a neutralstate with the accumulated elastic force through releasing of the torqueinput from the input-side member. The stationary-side member comprisesan inclined portion which abuts on the elastic member and swells to theelastic member side. The inclined portion is formed into a shape forcontrolling an amount of axial movement of the elastic member when theelastic member is restored to an initial state through the releasing ofthe torque input from the input-side member. Here, it is desired thatthe shape for controlling the amount of axial movement of the elasticmember when the elastic member is restored to the initial state throughthe releasing of the torque input from the input-side member be formedon a rounded corner surface situated at an outermost diameter of theinclined portion or on an inclined surface extending radially inwardfrom the outermost diameter of the inclined portion.

According to the present invention, the inclined portion is formed intothe shape for controlling the amount of axial movement of the elasticmember when the elastic member is restored to the initial state throughreleasing of the torque input from the input-side member. Thus, at thetime of lever operation of restoring a lever from a full stroke to aneutral position, it is possible to prevent the elastic member, whichslides on the stationary-side member, from climbing onto the inclinedportion of the stationary-side member, and to avoid contact of theelastic member with the input-side member. Accordingly, it is possibleto prevent occurrence of noises.

The lever-side clutch portion according to the present inventioncomprises: an input-side member to be rotated through the leveroperation; and an elastic member provided between a stationary-sidemember restricted in rotation and the input-side member, foraccumulating an elastic force obtained by torque input from theinput-side member and for restoring the input-side member to a neutralstate with the accumulated elastic force through releasing of the torqueinput from the input-side member. The elastic member comprises aC-shaped and band-like plate spring which comprises a pair of lockportions formed by bending both ends thereof to a radially outer side.One of the pair of lock portions and another of the pair of lockportions are formed at positions that are identical in a band-platewidth direction. Here, it is desired that the one of the pair of lockportions and the another of the pair of lock portions be formed atcenter positions in the band-plate width direction or at both sidepositions in the band-plate width direction.

According to the present invention, the elastic member comprises theC-shaped and band-like plate spring which comprises the pair of lockportions formed by bending both the ends thereof to the radially outerside, and one of the pair of lock portions and another of the pair oflock portions are formed at positions that are identical in theband-plate width direction. Thus, each end of the elastic member isshaped to be symmetric with respect to a center line in a band-plateperipheral direction, and hence it is possible to prevent a moment forcegenerated at the time of application of input torque. Accordingly, abehavior of the elastic member is stabilized, which can preventoccurrence of noises.

The brake-side clutch portion according to the present inventioncomprises: an output-side member from which torque is output; astationary-side member restricted in rotation; a coupling member towhich the torque is input from the lever-side clutch portion; and aplurality of pairs of engagement elements accommodated in pockets of thecoupling member, for controlling transmission of the torque input fromthe coupling member and interruption of torque reversely input from theoutput-side member through engagement with and disengagement from wedgegaps formed between the stationary-side member and the output-sidemember. Any one of width dimensions of the pockets and outer diameterdimensions of the plurality of pairs of engagement elements are setdifferent from one another.

According to the present invention, the width dimensions of the pocketsare set different from one another or the outer diameter dimensions ofthe plurality of pairs of engagement elements are set different from oneanother. Thus, when the engagement elements are disengaged from thewedge gaps so as to release a locked state of the output-side member,not all the engagement elements are disengaged from the wedge gaps atthe same time, but all the engagement elements are disengaged from thewedge gaps in a step-by-step manner. With this operation, even in a casewhere high load is applied to the output-side member, when the lockedstate of the output-side member is released, it is possible to avoidconcentration of contact pressure, which is generated between theengagement elements due to high load applied to the output-side member,on the engagement element disengaged from the wedge gap last.Accordingly, it is possible to suppress concentration of the contactpressure generated between the engagement elements, and to preventoccurrence of noises at the moment at which the engagement elements areflipped.

According to the present invention, as means for making a differenceamong the width dimensions of the pockets, the following structure isdesired: pockets having small widths and pockets having large widths arearranged alternately in a peripheral direction. With this structure,when the locked state of the output-side member is released, theengagement elements accommodated in the pockets having small widths aredisengaged from the wedge gaps prior to the engagement elementsaccommodated in the pockets having large widths. Thus, all theengagement elements can be disengaged from the wedge gaps substantiallyone side at a time in a step-by-step and balanced manner, andconcentration of the contact pressure generated between the engagementelements is suppressed easily.

According to the present invention, as means for making a differenceamong the outer diameter dimensions of the plurality of pairs ofengagement elements, the following structure is desired: engagementelements having small diameters and engagement elements having largediameters are arranged alternately in a peripheral direction. With thisstructure, when the locked state of the output-side member is released,the engagement elements having small diameters are disengaged from thewedge gaps prior to the engagement elements having large diameters.Thus, all the engagement elements can be disengaged from the wedge gapssubstantially one side at a time in a step-by-step and balanced manner,and concentration of the contact pressure generated between theengagement elements is suppressed easily.

In a case where the coupling member according to the present inventioncomprises seven or more pockets, it is desired that the seven or morepockets comprise three pockets having large widths and four or morepockets having small widths. With this structure, when the locked stateof the output-side member is released, the engagement elementsaccommodated in the four or more pockets having small widths aredisengaged from the wedge gaps, and then the engagement elementsaccommodated in the minimum necessary three remaining pockets havinglarge widths are disengaged from the wedge gaps. As a result,concentration of the contact pressure generated between the engagementelements is suppressed easily.

In a case where the coupling member according to the present inventioncomprises seven or more pockets, it is desired that the seven or morepockets accommodate three pairs of engagement elements having largediameters and four or more pairs of engagement elements having smalldiameters. With this structure, when the locked state of the output-sidemember is released, the four or more pairs of engagement elements aredisengaged from the wedge gaps, and then the minimum necessary threeremaining pairs of engagement elements are disengaged from the wedgegaps. As a result, concentration of the contact pressure generatedbetween the engagement elements is suppressed easily.

The brake-side clutch portion according to the present inventioncomprises: an output-side member from which torque is output; astationary-side member restricted in rotation; a plurality of pairs ofengagement elements arranged in wedge gaps between the stationary-sidemember and the output-side member, for controlling transmission of thetorque input from the lever-side clutch portion and interruption of thetorque reversely input from the output side through engagement anddisengagement between the stationary-side member and the output-sidemember; and an elastomer member inserted between the engagement elementsof each pair, for imparting a repulsive force to the engagement elementsof each pair.

According to the present invention, the elastomer member, which isinserted between the engagement elements of each pair, for imparting therepulsive force to the engagement elements of each pair, can easilyincrease load applied to the engagement elements. Accordingly, even in acase where high load is applied to the output-side member, when thelocked state of the output-side member is released, it is possible toforestall the situation that the elastomer member is to flip theengagement elements, and it is possible to inhibit occurrence of noises.

It is desired that the elastomer member according to the presentinvention have an outside dimension larger than a gap between theengagement elements of each pair, and be inserted in an elasticallydeformed state between the engagement elements of each pair. With thisstructure, an elastic restoring force of the elastomer member acts as arepulsive force to be imparted to the engagement elements, and hence therepulsive force is easily imparted to the engagement elements.

It is desired that the elastomer member according to the presentinvention have a columnar shape or a quadrangular prism shape, and havean axial dimension equal to or smaller than axial dimensions of theengagement elements of each pair. With this structure, owing to such asimple shape, a function of the elastomer member can be exerted. Whenthe elastomer member has the axial dimension equal to or smaller thanthe axial dimensions of the engagement elements of each pair, thefunction of the elastomer member can be exerted reliably, which iseffective.

It is desired that the elastomer member according to the presentinvention be made of any one of a thermosetting elastomer and anelastically deformable resin material. This selection of any one of thethermosetting elastomer and the elastically deformable resin materialenables easy manufacture of the elastomer member, which is effective.

In the clutch unit according to the present invention, the lever-sideclutch portion and the brake-side clutch portion are incorporated in anautomobile seat-lifter section. Thus, the clutch unit is suited for usein an automobile. In this case, the clutch unit has a configuration inwhich the input-side member is connected to an operation lever and theoutput-side member is coupled to a link mechanism of the automobileseat-lifter section.

Advantageous Effects of Invention

According to the present invention, the inclined portion is formed intothe shape for controlling the amount of axial movement of the elasticmember when the elastic member is restored to the initial state throughreleasing of the torque input from the input-side member. Thus, at thetime of lever operation of restoring a lever from a full stroke to aneutral position, it is possible to prevent the elastic member, whichslides on the stationary-side member, from climbing onto the inclinedportion of the stationary-side member, and to avoid contact of theelastic member with the input-side member. Accordingly, it is possibleto prevent occurrence of noises.

Further, the elastic member comprises the C-shaped and band-like platespring which comprises the pair of lock portions formed by bending boththe ends thereof to the radially outer side, and one of the pair of lockportions and another of the pair of lock portions are formed atpositions that are identical in the band-plate width direction. Thus,each end of the elastic member is formed into a symmetric shape, andhence it is possible to prevent such a moment force as to pivot theanother of the pair of lock portions about a fulcrum set on the one ofthe pair of lock portions at the time of application of input torque.Accordingly, a behavior of the elastic member is stabilized, which canprevent occurrence of noises.

As a result, it is possible to provide a clutch unit with highreliability. In a case where the clutch unit is incorporated into theautomobile seat-lifter section, lever operation of adjusting a seatvertically is performed satisfactorily, and hence comfortable leveroperation can be realized for a passenger.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A longitudinal sectional view of an overall structure of aclutch unit according to an embodiment of the present invention.

[FIG. 2] A right-hand side view of FIG. 1.

[FIG. 3] A left-hand side view of FIG. 1.

[FIG. 4] A sectional view taken along the line A-A of FIG. 1.

[FIG. 5] A sectional view taken along the line B-B of FIG. 1.

[FIG. 6 a] A sectional view of a lever-side side plate.

[FIG. 6 b] A left-hand side view of FIG. 6 a.

[FIG. 7 a] A sectional view illustrating an example of a lever-sideouter ring.

[FIG. 7 b] A left-hand side view of FIG. 7 a.

[FIG. 7 c] A right-hand side view of FIG. 7 a.

[FIG. 8 a] A sectional view of an inner ring.

[FIG. 8 b] A left-hand side view of FIG. 8 a.

[FIG. 9] A perspective view of a retainer.

[FIG. 10 a] A sectional view of the retainer.

[FIG. 10 b] A left-hand side view of FIG. 10 a.

[FIG. 10 c] A sectional view of FIG. 10 a.

[FIG. 11] A perspective view of an inner centering spring.

[FIG. 12 a] A perspective view illustrating an example of an outercentering spring.

[FIG. 12 b] A perspective view illustrating another example of the outercentering spring.

[FIG. 13 a] A perspective view of an output shaft seen from one side.

[FIG. 13 b] A perspective view of the output shaft seen from anotherside.

[FIG. 14 a] A sectional view of the output shaft.

[FIG. 14 b] A left-hand side view of FIG. 14 a.

[FIG. 14 c] A right-hand side view of FIG. 14 a.

[FIG. 15 a] A sectional view of a brake-side outer ring.

[FIG. 15 b] A left-hand side view of FIG. 15 a.

[FIG. 16 a] A sectional view of a cover.

[FIG. 16 b] A right-hand side view of FIG. 16 a.

[FIG. 17 a] A sectional view of a brake-side side plate.

[FIG. 17 b] A right-hand side view of FIG. 17 a.

[FIG. 18 a] A front view of a friction ring.

[FIG. 18 b] A left-hand side view of FIG. 18 a.

[FIG. 18 c] A right-hand side view of FIG. 18 a.

[FIG. 19 a] A perspective view illustrating a state before thebrake-side outer ring is assembled to the brake-side side plate.

[FIG. 19 b] A perspective view illustrating a state after the brake-sideouter ring is assembled to the brake-side side plate.

[FIG. 20] A perspective view illustrating a state in which thebrake-side outer ring and the cover are assembled to the brake-side sideplate.

[FIG. 21] A perspective view illustrating a state in which thebrake-side side plate, the brake-side outer ring, and the cover areintegrated with one another by swaging.

[FIG. 22] A sectional view taken along the line C-C of FIG. 1.

[FIG. 23 a] A perspective view illustrating a state before the retaineris assembled to the brake-side side plate, the brake-side outer ring,the cover, and the inner centering spring.

[FIG. 23 b] A perspective view illustrating a state after the retaineris assembled to the brake-side side plate, the brake-side outer ring,the cover, and the inner centering spring.

[FIG. 24] A longitudinal sectional view illustrating an overallstructure of a clutch unit according to another embodiment of thepresent invention.

[FIG. 25] An enlarged main part sectional view illustrating a state inwhich cylindrical rollers are flipped and thus a plate spring buckleswhen a locked state of the output shaft is released.

[FIG. 26] A sectional view illustrating a brake-side clutch portionaccording to another embodiment of the present invention, in which widthdimensions of pockets are set different.

[FIG. 27] An enlarged main part sectional view illustrating a state inwhich, under the state illustrated in FIG. 26, an inner ring pressescylindrical rollers accommodated in a pocket having a small width andthus the cylindrical rollers are disengaged from a wedge gap.

[FIG. 28] An enlarged main part sectional view illustrating a state inwhich, under the state illustrated in FIG. 27, the inner ring pressescylindrical rollers accommodated in a pocket having a large width andthus the cylindrical rollers are disengaged from a wedge gap.

[FIG. 29] A sectional view illustrating a brake-side clutch portionaccording to still another embodiment of the present invention, in whichouter diameter dimensions of cylindrical rollers are set different.

[FIG. 30] An enlarged main part sectional view illustrating a state inwhich, under the state illustrated in FIG. 29, the inner ring pressescylindrical rollers having small diameters and thus the cylindricalrollers are disengaged from a wedge gap.

[FIG. 31] An enlarged main part sectional view illustrating a state inwhich, under the state illustrated in FIG. 30, the inner ring pressescylindrical rollers having large diameters and thus the cylindricalrollers are disengaged from a wedge gap.

[FIG. 32] A sectional view illustrating a brake-side clutch portionaccording to still another embodiment of the present invention, in whichwidth dimensions of pockets are set different in a case of comprisingseven pockets.

[FIG. 33] A sectional view illustrating a brake-side clutch portionaccording to still another embodiment of the present invention, in whichouter diameter dimensions of cylindrical rollers are set different in acase of comprising seven pockets.

[FIG. 34] A sectional view illustrating a brake-side clutch portionaccording to still another embodiment of the present invention, in whichan elastomer member is inserted between cylindrical rollers of eachpair.

[FIG. 35] An enlarged main part sectional view of FIG. 34, forillustrating an embodiment in which an elastomer member having acolumnar shape is applied.

[FIG. 36] A sectional view illustrating a state in which, under thestate illustrated in FIG. 35, the inner ring presses cylindrical rollersand thus the cylindrical rollers are disengaged from a wedge gap.

[FIG. 37] A sectional view illustrating still another embodiment inwhich an elastomer member having a quadrangular prism shape is applied.

[FIG. 38] A conceptual view illustrating a seat of an automobile.

[FIG. 39 a] A conceptual view illustrating a structural example of aseat-lifter section.

[FIG. 39 b] An enlarged main part view of FIG. 39 a.

[FIG. 40] A longitudinal sectional view illustrating an overallstructure of a conventional clutch unit.

[FIG. 41] A lateral sectional view taken along the line D-D of FIG. 40.

[FIG. 42] A lateral sectional view taken along the line E-E of FIG. 40.

[FIG. 43] A perspective view illustrating an outer centering spring ofthe conventional clutch unit.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a longitudinal sectional view of an overall structure of aclutch unit X according to an embodiment of the present invention. FIG.2 is a right-hand side view of the clutch unit X illustrated in FIG. 1.FIG. 3 is a left-hand side view of the clutch unit X illustrated inFIG. 1. FIG. 4 is a lateral sectional view taken along the line A-A ofFIG. 1. FIG. 5 is a lateral sectional view taken along the line B-B ofFIG. 1. Further, FIGS. 6 to 18 illustrate main components of the clutchunit X. FIGS. 19 to 23 illustrate assembled states of the maincomponents of the clutch unit X.

The clutch unit X is incorporated into an automobile seat-lifter section(see FIGS. 38, 39 a, and 39 b) for adjusting a height of a seat throughlever operation or the like. As illustrated in FIGS. 1 to 5, the clutchunit X comprises a unit of a lever-side clutch portion 11 provided on aninput side and a brake-side clutch portion 12 which is provided on anoutput side and which has a function of interrupting reverse input.

As illustrated in FIGS. 1, 2, and 4, the lever-side clutch portion 11comprises a lever-side side plate 13 and a lever-side outer ring 14 eachserving as an input-side member to which an operation lever (not shown)or the like is connected, an inner ring 15 serving as a coupling memberwhich transmits torque from the lever-side outer ring 14 to thebrake-side clutch portion 12, a plurality of cylindrical rollers 16arranged as an example of engagement elements in wedge gaps 20 formedbetween an outer peripheral surface 15 a of the inner ring 15 and aninner peripheral surface 14 a of the lever-side outer ring 14, aretainer 17 for retaining the cylindrical rollers 16 equiangularly, aninner centering spring 18 as a first elastic member for restoring theretainer 17 to a neutral state, and an outer centering spring 19 as asecond elastic member for restoring the lever-side outer ring 14 to aneutral state. Note that, components are prevented from being detachedby press-fitting a washer 31 onto an end portion of an output shaft 22described later through intermediation of a wave washer 30 (see FIG. 1).

As illustrated in FIGS. 1, 3, and 5, the so-called lock type brake-sideclutch portion 12 which has a function of interrupting reverse inputmainly comprises the inner ring 15 serving as a coupling member to whichthe torque from the lever-side clutch portion 11 is input, the outputshaft 22 serving as an output-side member, a brake-side outer ring 23, acover 24, and a brake-side side plate 25 each serving as astationary-side member restricted in rotation, a plurality of pairs ofcylindrical rollers 27 arranged as engagement elements in wedge gaps 26between the brake-side outer ring 23 and the output shaft 22, forcontrolling transmission of the torque input from the inner ring 15 andinterruption of the torque reversely input from the output shaft 22through engagement and disengagement between both the members, and platesprings 28 of, for example, an N-shaped sectional configuration, eachinserted between the cylindrical rollers 27 of each pair and serving aselastic members for imparting repulsive force to the cylindrical rollers27. Note that, protrusions 22 f are provided to the output shaft 22 andinserted into holes 15 d with clearances, which are provided to theinner ring 15 (see FIG. 1).

Next, detailed description is made of main components of the lever-sideclutch portion 11 and the brake-side clutch portion 12 which areprovided in the clutch unit X.

FIGS. 6 a and 6 b illustrate the lever-side side plate 13 of thelever-side clutch portion 11. In the lever-side side plate 13, a hole 13a into which the output shaft 22 and the inner ring 15 are inserted isformed in a center portion thereof, and a plurality of (five, forexample) claw portions 13 b are provided in a protruding manner on anouter peripheral portion thereof. Those claw portions 13 b are bent andmolded in an axial direction so as to have bisected distal ends. Then,the claw portions 13 b are inserted into cutout recessed portions 14 e(see FIG. 7 c) of the lever-side outer ring 14, which are describedlater. Lastly, the distance between each of the bisected distal ends isincreased outward. In this manner, the lever-side side plate 13 is fixedto the lever-side outer ring 14 by swaging. Note that, in the figures, aplurality of (four, for example) holes for mounting the operation lever(not shown) for adjusting a height of a seat to the lever-side sideplate 13 are represented by reference symbol 13 c.

FIGS. 7 a to 7 c illustrate the lever-side outer ring 14. The lever-sideouter ring 14 is obtained by molding a plate-like material into acup-shape through press working, and comprises a hole 14 b formed in acenter portion 14 c, through which the output shaft 22 and the innerring 15 are inserted. On an inner periphery of a cylindrical portion 14d extending from the center portion 14 c in the axial direction, aplurality of cam surfaces 14 a are equiangularly formed (see FIG. 4).

On an outer peripheral portion of the lever-side outer ring 14, aplurality of (three, for example) claw portions 14 f and 14 g areprovided in a protruding manner and bent and molded in the axialdirection. Of those claw portions 14 f and 14 g, the one claw portion 14f is locked by being inserted and arranged between two lock portions 19a (see FIGS. 12 a and 12 b) of the outer centering spring 19 describedlater. In a state of being in contact with an end surface of thebrake-side outer ring 23 described later, the other two claw portions 14g slide on the end surface of the brake-side outer ring 23 in accordancewith rotation of the lever-side outer ring 14, and move between a pairof lock portions 24 e and 24 f (see FIG. 16 b) as rotation stoppersprovided on an outer periphery of the cover 24 so as to be abuttable onthe lock portion 24 e and 24 f, respectively, at moving ends in arotational direction. In this manner, an operating angle of theoperation lever is restricted.

The plurality of (five in the figure) cutout recessed portions 14 e intowhich the claw portions 13 b (see FIGS. 6 a and 6 b) of the lever-sideside plate 13 are inserted are formed on an outer periphery of thelever-side outer ring 14. By swaging the claw portions 13 b of thelever-side side plate 13, which are inserted into the cutout recessedportions 14 e, the lever-side side plate 13 and the lever-side outerring 14 are connected to each other. The lever-side outer ring 14 andthe lever-side side plate 13 fixed by swaging to the lever-side outerring 14 constitute the input-side member of the lever-side clutchportion 11.

FIGS. 8 a and 8 b illustrate the inner ring 15. The inner ring 15 isprovided with the outer peripheral surface 15 a formed on an outerdiameter of a cylindrical portion 15 b into which the output shaft 22 isinserted, the wedge gaps 20 (see FIG. 4) being formed between the outerperipheral surface 15 a and the cam surfaces 14 a of the lever-sideouter ring 14. Further, a larger diameter portion 15 c extending from anend portion of the cylindrical portion 15 b in a radially outerdirection and bending in the axial direction is integrally formed. Inorder to cause the larger diameter portion 15 c to function as aretainer for the brake-side clutch portion 12, pockets 15 e foraccommodating the cylindrical rollers 27 and the plate springs 28 areequiangularly formed in the larger diameter portion 15 c. Note that, inthe figures, holes into which the protrusions 22 f of the output shaft22 (see FIG. 1) are inserted with clearances are represented by areference symbol 15 d.

FIGS. 9, and 10 a to 10 c illustrate the retainer 17 made of a resin.The retainer 17 is a cylindrical member in which a plurality of pockets17 a for accommodating the cylindrical rollers 16 are equiangularlyformed. Two cutout recessed portions 17 b are formed in one end portionof the retainer 17, and lock portions 18 a of the above-mentioned innercentering spring 18 are locked to two adjacent end surfaces 17 c of therespective cutout recessed portions 17 b (see FIG. 22).

FIG. 11 illustrates the inner centering spring 18. The inner centeringspring 18 is a spring having a circular C-shape in cross-section andcomprising a pair of the lock portions 18 a bent to a radially innerside, and is situated on the radially inner side of the outer centeringspring 19 (see FIG. 22). The inner centering spring 18 is arrangedbetween the retainer 17 and the cover 24 serving as a stationary-sidemember of the brake-side clutch portion 12. In addition, both the lockportions 18 a are locked to the two end surfaces 17 c (see FIGS. 9 and10 b) of the retainer 17 and locked to a claw portion 24 b (see FIGS. 16a and 16 b) provided to the cover 24 (see FIGS. 22, 23 a and 23 b).

At the time of application of torque input from the lever-side outerring 14 in the inner centering spring 18, one of the lock portions 18 ais engaged with one of the end surfaces 17 c of the retainer 17, and theother of the lock portions 18 a is engaged with the claw portion 24 b ofthe cover 24. Thus, the inner centering spring 18 is pressed andextended in accordance with rotation of the lever-side outer ring 14 soas to accumulate an elastic force. At the time of releasing the torqueinput from the lever-side outer ring 14, the retainer 17 is restored toa neutral state with the elastic restoring force.

FIG. 12 a illustrates an example of the outer centering spring 19. Theouter centering spring 19 is a C-shaped and band plate-like springcomprising the pair of lock portions 19 a formed by bending both theends thereof to a radially outer side, and is situated on a radiallyouter side of the inner centering spring 18 (see FIG. 22). The outercentering spring 19 is arranged between the lever-side outer ring 14 ofthe lever-side clutch portion 11 and the cover 24 of the brake-sideclutch portion 12. Both the lock portions 19 a are locked to the clawportion 14 f (see FIGS. 7 a to 7 c) provided to the lever-side outerring 14, and also locked to a claw portion 24 d (see FIGS. 16 a and 16b) provided to the cover 24 (see FIGS. 23 a and 23 b). The lock portions19 a are arranged while being displaced (by 180°) in a circumferentialdirection with respect to the lock portions 18 a of the inner centeringspring 18 (see FIG. 22).

In the outer centering spring 19, when the torque input from thelever-side side plate 13 is applied through lever operation so as torotate the lever-side outer ring 14, one of the lock portions 19 a isengaged with the claw portion 14 f of the lever-side outer ring 14, andthe other of the lock portions 19 a is engaged with the claw portion 24d of the cover 24, respectively. Thus, the outer centering spring 19 ispressed and extended in accordance with the rotation of the lever-sideouter ring 14 so as to accumulate an elastic force. After the outercenter spring 19 is increased in diameter, when the torque input fromthe lever-side outer ring 14 is released, the lever-side outer ring 14is restored to a neutral state with the elastic restoring force.

Unlike in the conventional outer centering spring 119 (see FIG. 43), inthe outer centering spring 19 illustrated in FIG. 12 a, one of the lockportions 19 a and the other of the lock portions 19 a are formed atcenter positions that are identical in a band-plate width direction.That is, one of the lock portions 19 a and the other of the lockportions 19 a are formed in such a manner that two slits are formed ineach end of the outer centering spring 19 in a peripheral direction anda center part situated between the two slits is bent to a radially outerside. Thus, each end of the outer centering spring 19 is shaped to besymmetric with respect to a center line in a band-plate peripheraldirection, and hence it is possible to prevent a moment force generatedat the time of application of input torque, i.e., such a force as topivot the other of the lock portions 19 a about a fulerum set on one ofthe lock portions 19 a. Accordingly, a behavior of the outer centeringspring 19 is stabilized, which can prevent occurrence of noises.

Note that, it is only necessary that each end of the outer centeringspring 19 be shaped to be symmetric with respect to the center line inthe band-plate peripheral direction, and hence, for example, an outercentering spring 19′ as illustrated in FIG. 12 b may be employed. Theouter centering spring 19′ is a C-shaped and band-like plate springwhich comprises a pair of lock portions 19 a′ formed by bending each endthereof to the radially outer side. One of the lock portions 19 a′ andthe other of the lock portions 19 a′ are formed at both side positionsthat are identical in the band-plate width direction. That is, one ofthe lock portions 19 a′ and the other of the lock portions 19 a′ areformed in such a manner that two slits are formed in each end of theouter centering spring 19′ in the peripheral direction and both sideparts situated on the outer side of the two slits are bent to theradially outer side. Also in this case, it is possible to prevent amoment force generated at the time of application of input torque, i.e.,such a force as to pivot the other of the lock portions 19 a′ about afulerum set on one of the lock portions 19 a′. Accordingly, a behaviorof the outer centering spring 19′ is stabilized, which can preventoccurrence of noises.

FIGS. 13 a and 13 b and FIGS. 14 a to 14 c illustrate the output shaft22. The output shaft 22 comprises a larger diameter portion 22 d whichextends from a shaft portion 22 c to the radially outer side to beincreased in diameter, and is integrally formed substantially in anaxial center region of the output shaft 22. A pinion gear 41 g to becoupled to a seat-lifter section 41 is coaxially formed on a distal endof the shaft portion 22 c.

A plurality of (six, for example) flat cam surfaces 22 a areequiangularly formed on an outer peripheral surface of the largerdiameter portion 22 d, and the two cylindrical rollers 27 and the platespring 28 are arranged in each wedge gap 26 (see FIG. 5) providedbetween the cam surfaces 22 a and an inner peripheral surface 23 b ofthe brake-side outer ring 23. In one end surface of the larger diameterportion 22 d, there is formed an annular recessed portion 22 b in whicha friction ring 29 is accommodated and arranged. Further, in thefigures, protrusions formed on the other end surface of the largerdiameter portion 22 d are represented by reference symbol 22 f, theprotrusions being inserted into the holes 15 d of the inner ring 15 withclearances (see FIGS. 1, 8 a, and 8 b).

FIGS. 15 a and 15 b illustrate the brake-side outer ring 23, and FIGS.16 a and 16 b illustrate the cover 24. FIGS. 17 a and 17 b illustratethe brake-side side plate 25. The brake-side outer ring 23 and the cover24 described above are integrally fixed to each other with thebrake-side side plate 25 by swaging. The brake-side outer ring 23 isformed of a thick plate-like member obtained by punching of a singlematerial with a press, and the cover 24 is molded by pressing of anothersingle material. As illustrated in FIGS. 16 a and 16 b, the cover 24 hasan inclined portion 24 g, which swells to the outer centering spring 19side in a state of abutting on the larger diameter portion 15 c of theinner ring 15 described above (see FIG. 1). Note that, in the figures,holes into which the output shaft 22 is inserted are represented byreference symbols 24 c and 25 b, and holes to which protrusions 29 a ofthe friction ring 29 described later are fitted are represented byreference symbol 25 c.

The clutch unit X has the following structure. Specifically, the outercentering spring 19 is arranged between the cover 24 and the lever-sideouter ring 14, and the outer centering spring 19 abuts on the cover 24on the radially outer side of the inclined portion 24 g of the cover 24.Here, at the time of lever operation of restoring a lever from a fullstroke to a neutral position, the outer centering spring 19, whichslides on the cover 24, climbs onto the inclined portion 24 g of thecover 24 and thus comes into contact with the opposing lever-side outerring 14. As a result, slight noises may occur. Accordingly, the inclinedportion 24 g of the cover 24 is formed into a shape for controlling anamount of axial movement of the outer centering spring 19 when the outercentering spring 19 is restored to an initial state by releasing ofinput torque.

That is, according to the embodiment illustrated in FIG. 1, a curvatureradius of a rounded corner surface 24 g ₁ situated at an outermostdiameter of the inclined portion 24 g of the cover 24 is set larger thana curvature radius of a rounded corner surface 124 g ₁ situated at anoutermost diameter of the inclined portion 124 g of the conventionalcover 124 (see FIG. 40). Thus, a swelling height of the inclined portion24 g is changed gradually with respect to a radial change of the outercentering spring 19 when the outer centering spring 19 climbs onto theinclined portion 24 g of the cover 24 at the time of lever operation ofrestoring the lever from a full stroke to a neutral position, and thusthe amount of axial movement of the outer centering spring 19 can becontrolled. As a result, it is possible to prevent the outer centeringspring 19 from climbing onto the inclined portion 24 g of the cover 24,and to avoid contact of the outer centering spring 19 with thelever-side outer ring 14. Therefore, it is possible to preventoccurrence of noises.

Further, as another embodiment, as illustrated in FIG. 24, an angle ofan inclined surface 24 g ₂ extending radially inward from the outermostdiameter of the inclined portion 24 g of the cover 24 may be set smallerthan an angle of an inclined surface 124 g ₂ extending radially inwardfrom the outermost diameter of the inclined portion 124 g of theconventional cover 124 (see FIG. 40). Thus, the swelling height of theinclined portion 24 g is changed gradually with respect to the radialchange of the outer centering spring 19 when the outer centering spring19 climbs onto the inclined portion 24 g of the cover 24 at the time oflever operation of restoring the lever from a full stroke to a neutralposition, and thus the amount of axial movement of the outer centeringspring 19 can be controlled. As a result, it is possible to prevent theouter centering spring 19 from climbing onto the inclined portion 24 gof the cover 24, and to avoid contact of the outer centering spring 19with the lever-side outer ring 14. Therefore, it is possible to preventoccurrence of noises.

A plurality of (three) cutout recessed portions 23 a are formed on anouter periphery of the brake-side outer ring 23. Correspondingly to thecutout recessed portions 23 a, a plurality of (three) cutout recessedportions 24 a are similarly formed on an outer periphery of the cover24. As illustrated in FIGS. 19 a and 19 b, claw portions 25 a of thebrake-side side plate 25 are inserted into the cutout recessed portions23 a of the brake-side outer ring 23, respectively. Further, asillustrated in FIG. 20, the claw portions 25 a of the brake-side sideplate 25 are inserted into the cutout recessed portions 24 a of thecover 24, respectively.

The claw portions 25 a of the brake-side side plate 25 are inserted intothe cutout recessed portions 23 a and 24 a. By swaging the claw portions25 a of the brake-side side plate 25, the brake-side outer ring 23 andthe cover 24 are coupled to each other and integrated with thebrake-side side plate 25, to thereby form the stationary-side member.Swaging of the claw portions 25 a of the brake-side side plate 25 isperformed by increasing outward the distance between bisected distal endportions 25 a ₁ of each of the claw portions 25 a with use of a swage(not shown) (see FIG. 21).

The wedge gaps 26 are formed between the inner peripheral surface 23 bof the brake-side outer ring 23 and the cam surfaces 22 a of the outputshaft 22 (see FIG. 5). The cover 24 is provided with the claw portion 24b protruding in the axial direction, the claw portion 24 b beingarranged between the two lock portions 18 a of the inner centeringspring 18 of the lever-side clutch portion 11 (see FIGS. 11, 23 a, and23 b). The claw portion 24 b of the cover 24 is formed by raising thesurface of the cover 24 on the radially outer side of theclaw-portion-formation position. The claw portion 24 d protruding in theaxial direction is formed on the outer periphery of the cover 24. Theclaw portion 24 d is arranged between the two lock portions 19 a of theouter centering spring 19 of the lever-side clutch portion 11 (see FIGS.12 a, 23 a and 23 b).

Two pairs of the lock portions 24 e and 24 f are formed by stepping onthe outer periphery of the cover 24 (see FIGS. 23 a and 23 b). In astate in which the cover 24 is held in contact with the end surface ofthe brake-side outer ring 23, in accordance with rotation of thelever-side outer ring 14, the lock portions 24 e and 24 f are allowed tobe brought into abutment, in a rotational direction, on the clawportions 14 g, which slide on the end surface of the brake-side outerring 23. As a result, the lock portions 24 e and 24 f function asrotation stoppers for restricting an operating angle of the operationlever. In other words, when the lever-side outer ring 14 is rotatedthrough operation of the operation lever, the claw portions 14 g thereofmove along the outer periphery of the cover 24 between the lock portions24 e and 24 f of the cover 24.

On the outer periphery of the brake-side sideplate 25, one flangeportion 25 e and two flange portions 25 f are provided as clutchmounting portions with respect to the seat-lifter section (see FIGS. 2to 4). In distal end portions of those three flange portions 25 e and 25f, there are formed, by boring, mounting holes 25 g and 25 h forallowing mounting with respect to the seat-lifter section, and there areprotrudingly formed, in the axial direction, cylindrical portions 25 iand 25 j in a manner of surrounding the mounting holes 25 g and 25 h.

FIGS. 18 a to 18 c illustrate the friction ring 29 made of a resin. Onan end surface of the friction ring 29, the plurality of circularprotrusions 29 a are equiangularly formed. By press-fitting and engagingthe protrusions 29 a into the holes 25 c of the brake-side side plate25, the friction ring 29 is fixed to the brake-side side plate 25 (seeFIGS. 1 and 3).

In the case of press-fitting of the protrusions 29 a, an engagementstate with the holes 25 c can be achieved due to elastic deformation ofthe protrusions 29 a made of a resin material. By adopting a press-fitengagement structure of the protrusions 29 a and the holes 25 c, it ispossible to prevent the friction ring 29 from falling off from thebrake-side side plate 25 due to handling during transportation or thelike. As a result, it is possible to increase handling properties at thetime of assembly.

The friction ring 29 is press-fitted to an inner peripheral surface 22 eof the annular recessed portion 22 b formed in the larger diameterportion 22 d of the output shaft 22 with fastening allowance (see FIGS.13 a, 14 a and 14 b). Due to a frictional force generated between anouter peripheral surface 29 c of the friction ring 29 and the innerperipheral surface 22 e of the annular recessed portion 22 b of theoutput shaft 22, rotational resistance is imparted to the output shaft22.

On the outer peripheral surface 29 c of the friction ring 29, there areequiangularly formed a plurality of recessed groove-like slits 29 b (seeFIG. 5). With provision of the slits 29 b as in this case, elasticitymay be imparted to the friction ring 29. Thus, a rate of change insliding torque is not increased with respect to inner diameter toleranceof the output shaft 22 and outer diameter tolerance of the friction ring29.

In other words, it is possible to reduce a setting range of rotationalresistance imparted by the frictional force generated between the outerperipheral surface 29 c of the friction ring 29 and the inner peripheralsurface 22 e of the annular recessed portion 22 b of the output shaft22, and hence to appropriately and easily set the degree of therotational resistance. Further, the slits 29 b serve as grease pools,and hence it is possible to suppress abrasion of the outer peripheralsurface 29 c of the friction ring 29 due to sliding with respect to theinner peripheral surface 22 e of the annular recessed portion 22 b ofthe output shaft 22.

Description is made on operation of the lever-side clutch portion 11 andthe brake-side clutch portion 12 of the clutch unit X structured asdescribed above.

In the lever-side clutch portion 11, when the input torque is applied tothe lever-side outer ring 14, the cylindrical rollers 16 are engagedinto the wedge gaps 20 between the lever-side outer ring 14 and theinner ring 15. The inner ring 15 is rotated with torque transmitted tothe inner ring 15 through the intermediation of the cylindrical rollers16. Simultaneously, an elastic force is accumulated in both thecentering springs 18 and 19 in accordance with the rotation of thelever-side outer ring 14 and the retainer 17. When the input torque isinterrupted, the lever-side outer ring 14 and the retainer 17 arerestored to a neutral state with the elastic force of both the centeringsprings 18 and 19. Meanwhile, the inner ring 15 is maintained at thefixed rotational position. Accordingly, the inner ring 15 is rotated inan inching manner with repetitive rotation of the lever-side outer ring14, in other words, pumping operation of the operation lever.

In the brake-side clutch portion 12, when reverse-input torque is inputto the output shaft 22, the plate spring 28 imparts a repulsive force tothe cylindrical rollers 27 of each pair, and thus the cylindricalrollers 27 are engaged into the wedge gap 26 between the output shaft 22and the brake-side outer ring 23 so as to lock the output shaft 22 withrespect to the brake-side outer ring 23. Therefore, the torque reverselyinput from the output shaft 22 is locked by the brake-side clutchportion 12 so as to interrupt back-flow of the torque reversely input tothe lever-side clutch portion 11.

Meanwhile, the torque input from the lever-side outer ring 14 is inputto the inner ring 15 through the intermediation of the lever-side clutchportion 11. When the inner ring 15 is brought into abutment on thecylindrical rollers 27 and presses the cylindrical rollers 27 againstthe elastic force of the plate springs 28, the cylindrical rollers 27are disengaged from the wedge gaps 26 and a locked state of the outputshaft 22 is released. As a result, the output shaft 22 is allowed to berotated. When the inner ring 15 is further rotated, clearances betweenthe holes 15 d of the inner ring 15 and the protrusions 22 f of theoutput shaft 22 are narrowed, and the inner ring 15 is brought intoabutment on the protrusions 22 f of the output shaft 22 in a rotationaldirection. As a result, the torque input from the inner ring 15 istransmitted to the output shaft 22 through the intermediation of theprotrusions 22 f, and the output shaft 22 is rotated.

Here, in a case where high load is applied to the output shaft 22,contact pressure generated between the cylindrical rollers 27 isincreased. As a result, when the cylindrical rollers 27 are disengagedfrom the wedge gap 26 so as to release a locked state of the outputshaft 22, as illustrated in FIG. 25, one engaging cylindrical roller(cylindrical roller 27 on the left side of FIG. 25), which is pressed bythe larger diameter portion 15 c of the inner ring 15 functioning as theretainer, is flipped toward the other cylindrical roller (cylindricalroller 27 on the right side of FIG. 25), and thus the plate spring 28may buckle. When the plate spring 28 buckles in this manner, each of thecylindrical rollers 27 cannot be restored to an initial position afterreleasing the locking. Further, there is a fear in that vibrationgenerated at the moment at which the cylindrical rollers 27 are flippedcauses noises.

In the clutch unit according to the above-mentioned embodiment, all thepockets 15 e are set to have the same circumferential width dimensions,the pockets 15 e being formed equiangularly in the larger diameterportion 15 c of the inner ring 15, for accommodating the cylindricalrollers 27 and the plate springs 28. However, as well as the widthdimensions of the pockets 15 e, an inner diameter dimension of thebrake-side outer ring 23, a roundness of the inner diameter of thebrake-side outer ring 23, outer diameter dimensions of the cylindricalrollers 27, and a cam surface dimension of the output shaft 22 vary.Accordingly, when the cylindrical rollers 27 are disengaged from thewedge gaps 26 so as to release the locked state of the output shaft 22,it may be difficult to disengage all the cylindrical rollers 27 from thewedge gaps 26 at the same time.

As described above, in a case where it is difficult to disengage all thecylindrical rollers 27 from the wedge gaps 26 at the same time, when thecylindrical rollers 27 are disengaged from the wedge gaps 26 so as torelease the locked state of the output shaft 22, the contact pressure,which is generated between the cylindrical rollers 27 due to high loadapplied to the output shaft 22, is concentrated on the cylindricalroller 27 that is disengaged from the wedge gap 26 last. As a result,the cylindrical rollers 27 are flipped, and hence the plate springs 28are more likely to buckle. Accordingly, it is extremely difficult torestore each of the cylindrical rollers 27 to an initial position, andnoises are more likely to occur at the moment at which the cylindricalrollers 27 are flipped.

In this context, when the locked state of the output shaft 22 isreleased, in order to suppress concentration of the contact pressuregenerated between the cylindrical rollers 27, and to prevent occurrenceof noises at the moment at which the cylindrical rollers 27 are flipped,in the clutch unit according to this embodiment, as illustrated in FIG.26, width dimensions W₁ of pockets 15 e ₁ are set different from widthdimensions W₂ of pockets 15 e ₂ (W₁<W₂). That is, the pockets 15 e ₁having small widths and the pockets 15 e ₂ having large widths arearranged alternately in the peripheral direction. As described above,the pockets 15 e ₁ having small widths and the pockets 15 e ₂ havinglarge widths are arranged alternately in the peripheral direction, andhence when the cylindrical rollers 27 are disengaged from the wedge gaps26 so as to release the locked state of the output shaft 22, not all thecylindrical rollers 27 are disengaged from the wedge gaps 26 at the sametime, but the following operation is provided instead. Specifically, asillustrated in FIG. 27, by being pressed by the larger diameter portion15 c of the inner ring 15, the cylindrical rollers 27 accommodated inthe pocket 15 e ₁ having a small width are disengaged from the wedge gap26 prior to the cylindrical rollers 27 accommodated in the pocket 15 e ₂having a large width. Then, as illustrated in FIG. 28, by being pressedby the larger diameter portion 15 c of the inner ring 15, thecylindrical rollers 27 accommodated in the pocket 15 e ₂ having thelarge width are disengaged from the wedge gap 26. In this way, all thecylindrical rollers 27 are disengaged from the wedge gaps 26 one side ata time in a step-by-step and balanced manner.

Besides setting of the width dimensions W₁ of the pockets 15 e ₁ to bedifferent from the width dimensions W₂ of the pockets 15 e ₂ as in thisembodiment, as another embodiment, as illustrated in FIG. 29, outerdiameter dimensions D₁ of cylindrical rollers 27 a of each pair may beset different from outer diameter dimensions D₂ of cylindrical rollers27 b of each pair (D₁<D₂). That is, the cylindrical rollers 27 a havingsmall diameters (outer diameter dimensions D₁) and the cylindricalrollers 27 b having large diameters (outer diameter dimensions D₂) maybe arranged alternately in the peripheral direction. As described above,the cylindrical rollers 27 a having small diameters and the cylindricalrollers 27 b having large diameters are arranged alternately in theperipheral direction, and hence the following operation is provided.Specifically, when the locked state of the output shaft 22 is released,as illustrated in FIG. 30, by being pressed by the larger diameterportion 15 c of the inner ring 15, the cylindrical rollers 27 a havingsmall diameters are disengaged from the wedge gap 26 prior to thecylindrical rollers 27 b having large diameters. Then, as illustrated inFIG. 31, by being pressed by the larger diameter portion 15 c of theinner ring 15, the cylindrical rollers 27 b having large diameters aredisengaged from the wedge gap 26. In this way, all the cylindricalrollers 27 a and 27 b are disengaged from the wedge gaps 26 one side ata time in a step-by-step and balanced manner.

As described above, the pockets 15 e ₁ having small widths and thepockets 15 e ₂ having large widths are arranged alternately in theperipheral direction, or the cylindrical rollers 27 a having smalldiameters and the cylindrical rollers 27 b having large diameters arearranged alternately in the peripheral direction, and thus the followingoperation is provided. Specifically, even in a case where high load isapplied to the output shaft 22, when the locked state of the outputshaft 22 is released, it is possible to avoid concentration of thecontact pressure, which is generated between the cylindrical rollers 27(27 a, 27 b) due to high load applied to the output shaft 22, on thecylindrical roller 27 (27 a, 27 b) that is disengaged from the wedge gap26 last. Accordingly, it is possible to suppress concentration of thecontact pressure generated between the cylindrical rollers 27 (27 a, 27b), and to prevent occurrence of noises at the moment at which thecylindrical rollers (27 a, 27 b) are flipped.

Note that, in the above-mentioned embodiments, description is made of acase where six pockets 15 e ₁ and 15 e ₂ (15 e) are provided. In a casewhere the larger diameter portion 15 c of the inner ring 15 functioningas the retainer comprises seven or more pockets 15 e ₁ and 15 e ₂ (15e), the following structure is adopted.

In the structure in which the width dimensions W₁ of the pockets 15 e ₁are set different from the width dimensions W₂ of the pockets 15 e ₂, ina case where eight pockets 15 e ₁ and 15 e ₂ are provided as in anembodiment illustrated in FIG. 32, three pockets 15 e ₂ having largewidths and four or more (five in this embodiment) pockets 15 e ₁ havingsmall widths are provided. With this structure, when the locked state ofthe output shaft 22 is released, the cylindrical rollers 27 accommodatedin the four or more (five) pockets 15 e ₁ having small widths aredisengaged from the wedge gaps 26, and then the cylindrical rollers 27accommodated in the minimum necessary three remaining pockets 15 e ₂having large widths are disengaged from the wedge gaps 26. As a result,concentration of the contact pressure generated between the cylindricalrollers 27 is suppressed easily.

Further, in the structure in which the outer diameter dimensions D₁ ofthe cylindrical rollers 27 a are set different from the outer diameterdimensions D₂ of the cylindrical rollers 27 b, in a case where eightpockets 15 e are provided as in an embodiment illustrated in FIG. 33,three pairs of cylindrical rollers 27 b having large diameters and fouror more pairs (five pairs in this embodiment) of cylindrical rollers 27a having small diameters are provided. With this structure, when thelocked state of the output shaft 22 is released, the four or more pairs(five pairs) of cylindrical rollers 27 a having small diameters aredisengaged from the wedge gaps 26, and then the minimum necessary threeremaining pairs of cylindrical rollers 27 b having large diameters aredisengaged from the wedge gaps 26. As a result, concentration of thecontact pressure generated between the cylindrical rollers 27 a, 27 b ofeach pair is suppressed easily.

In the above-mentioned embodiments, the output shaft 22 is locked by anelastic force of the plate spring 28, and the locked state of the outputshaft 22 is released against the elastic force of the plate spring 28.Because of a shape, a plate thickness, and the like of the plate spring28, spring load of the plate spring 28 has limitations with respect toload applied to the cylindrical rollers 27. Therefore, in a case whereload applied to the cylindrical rollers 27 is increased, it is necessaryto prepare means other than the plate spring 28.

In this context, when the locked state of the output shaft 22 isreleased, in order to forestall the situation that the cylindricalrollers 27 are flipped and thus the plate springs 28 may buckle, and toprevent occurrence of noises caused by vibration at the moment at whichthe cylindrical rollers 27 are flipped, instead of the plate springs 28used in the above-mentioned embodiments, as illustrated in FIG. 34, anelastomer member 28 a for imparting a repulsive force to the cylindricalrollers 27 of each pair may be inserted between the cylindrical rollers27 of each pair.

The elastomer member 28 a has an outer diameter dimension larger than agap between the cylindrical rollers 27 of each pair, and is inserted inan elastically deformed state between the cylindrical rollers 27 (seeFIG. 35). That is, as illustrated in FIG. 35, regions of the elastomermember 28 a abutting on the cylindrical rollers 27 are elasticallydeformed and dented by a pressing force applied from the cylindricalrollers 27. With this, an elastic restoring force of the elastomermember 28 a acts as a repulsive force to be imparted to the cylindricalrollers 27, and hence the repulsive force is easily imparted to thecylindrical rollers 27.

Further, the elastomer member 28 a has a columnar shape and an axialdimension equal to or smaller than axial dimensions of the cylindricalrollers 27. Owing to a simple shape such as the columnar shape, afunction of the elastomer member 28 a, i.e., a function of imparting therepulsive force to the cylindrical rollers 27 can be exerted. Further,when the axial dimension of the elastomer member 28 a is set equal to orsmaller than the axial dimensions of the cylindrical rollers 27, theelastomer member 28 a can reliably exert the function of imparting therepulsive force to the cylindrical rollers 27 without interfering withother components.

As described above, the output shaft 22 is locked by the elastic forceof the elastomer member 28 a, and the locked state of the output shaft22 is released against the elastic force of the elastomer member 28 a.In this embodiment, compared to the plate spring 28 (see FIG. 5), theelastomer member 28 a inserted between the cylindrical rollers 27 ofeach pair and having the function of imparting the repulsive force tothe cylindrical rollers 27 can easily increase the load applied to thecylindrical rollers 27.

As a result, even in a case where high load is applied to the outputshaft 22, when the cylindrical rollers 27 are disengaged from the wedgegaps 26 so as to release the locked state of the output shaft 22, thefollowing operation is provided. Specifically, as illustrated in FIG.36, owing to the elastomer member 28 a that does not buckle unlike theplate spring 28 (see FIG. 25), one engaging cylindrical roller(cylindrical roller 27 on the left side of FIG. 36) pressed by the innerring 15 is not flipped toward the other cylindrical roller (cylindricalroller 27 on the right side of FIG. 36), and the elastomer member 28 acan reliably restore each of the cylindrical rollers 27 to an initialposition after releasing the locking. Accordingly, it is possible toprevent occurrence of noises caused by vibration at the moment at whichthe cylindrical rollers 27 are flipped.

Note that, the elastomer member 28 a is made of any one of athermosetting elastomer and an elastically deformable resin material.This selection of anyone of the thermosetting elastomer and theelastically deformable resin material enables easy manufacture of theelastomer member 28 a. Further, as illustrated in FIG. 37, the elastomermember 28 b may have a quadrangular prism shape, and a sectional shapeof the elastomer member may be set arbitrarily.

The clutch unit X provided with the structure as described above indetail is used while being incorporated into, for example, an automobileseat-lifter section. FIG. 38 illustrates a seat 40 installed in a cabinof an automobile. The seat 40 comprises a sitting seat 40 a, a backrestseat 40 b, and the seat-lifter section 41 for adjusting a height H ofthe sitting seat 40 a. Adjustment of the height H of the sitting seat 40a is performed with an operation lever 41 a of the seat-lifter section41.

FIG. 39 a is a conceptual view of a structural example of theseat-lifter section 41. One ends of link members 41 c and 41 d arepivotally mounted to a slide movable member 41 b ₁ of a seat slideadjuster 41 b. The other ends of the link members 41 c and 41 d arepivotally mounted to the sitting seat 40 a. The other end of the linkmember 41 c is pivotally mounted to a sector gear 41 f throughintermediation of a link member 41 e. The sector gear 41 f is pivotallymounted to the sitting seat 40 a, and pivotable about a fulcrum 41 f ₁.The other end of the link member 41 d is pivotally mounted to thesitting seat 40 a.

The clutch unit X described above in this embodiment is fixed to anappropriate position of the sitting seat 40 a. Fixation of the clutchunit X to the sitting seat 40 a is fixation by swaging to a seat frame(not shown) of the sitting seat 40 a, in which the three flange portions25 e and 25 f of the brake-side side plate 25 are subjected to plasticdeformation in such a manner that the distal end portions of thecylindrical portions 25 i and 25 j are increased in diameter outward.

Meanwhile, the operation lever 41 a made of, for example, a resin iscoupled to the lever-side side plate 13 of the lever-side clutch portion11, and the pinion gear 41 g meshing with the sector gear 41 f as arotary member is provided to the output shaft 22 of the brake-sideclutch portion 12. As illustrated in FIGS. 1, 13 a, 13 b, 14 a, and 14b, the pinion gear 41 g is integrally formed at a distal end portion ofthe shaft portion 22 c of the output shaft 22.

In FIG. 39 b, when the operation lever 41 a is pivoted counterclockwise(upward), torque input in that direction is transmitted to the piniongear 41 g through intermediation of the clutch unit X so that the piniongear 41 g pivots counterclockwise. Then, the sector gear 41 f meshingwith the pinion gear 41 g pivots clockwise so as to pull the other endof the link member 41 c through intermediation of the link member 41 e.As a result, the link member 41 c and the link member 41 d standtogether, and a seat surface of the sitting seat 40 a becomes higher.

In this manner, when the operation lever 41 a is released afteradjustment of the height H of the sitting seat 40 a, the operation lever41 a pivots clockwise with the elastic force of the two centeringsprings 18 and 19, and returns to the original position (restores to theneutral state). Note that, when the operation lever 41 a is pivotedclockwise (downward), the seat surface of the sitting seat 40 a islowered through operation in an opposite direction as that in the casedescribed above. Further, when the operation lever 41 a is releasedafter adjustment of the height, the operation lever 41 a pivotscounterclockwise and returns to the original position (restores to theneutral state).

The present invention is not limited to the above-mentioned embodiments.As a matter of course, the present invention may be carried out invarious modes without departing from the spirit of the presentinvention. The scope of the present invention is defined by claims, andincludes the meaning of an equivalent of the claims and all themodifications within the claims.

1-3. (canceled)
 4. A clutch unit, comprising: a lever-side clutchportion provided on an input side, for controlling transmission andinterruption of rotational torque to an output side through leveroperation; and a brake-side clutch portion provided on the output side,for transmitting torque input from the lever-side clutch portion to theoutput side and for interrupting torque reversely input from the outputside, wherein: the lever-side clutch portion comprises: an input-sidemember to be rotated through the lever operation; and an elastic memberprovided between a stationary-side member restricted in rotation and theinput-side member, for accumulating an elastic force obtained by torqueinput from the input-side member and for restoring the input-side memberto a neutral state with the accumulated elastic force through releasingof the torque input from the input-side member, the elastic membercomprises a C-shaped and band-like plate spring which comprises a pairof lock portions formed by bending both ends thereof to a radially outerside; and one of the pair of lock portions and another of the pair oflock portions are formed at positions that are identical in a band-platewidth direction.
 5. A clutch unit according to claim 4, wherein the oneof the pair of lock portions and the another of the pair of lockportions are formed at center positions in the band-plate widthdirection.
 6. A clutch unit according to claim 4, wherein the one of thepair of lock portions and the another of the pair of lock portions areformed at both side positions in the band-plate width direction. 7-18.(canceled)
 19. A clutch unit according to claim 4, wherein thelever-side clutch portion and the brake-side clutch portion areincorporated in an automobile seat-lifter section.